1. Field of the Invention
The present invention relates an ultrasonic motor drive apparatus.
2. Description of the Related Art
An ultrasonic motor has a vibration member including an ultrasonic vibrator and a moving member that is in contact with the vibration member. Vibration is induced in a vibration member with the application of voltage, whereby a moving member (which will be sometimes referred to as a “driven member” hereinafter) is driven by the vibration by friction. Ultrasonic motors having a spherical driven member through which output power is transmitted are used as drive sources having multiple degrees of freedom in apparatuses such as robot arms and articulated mechanisms. Other various applications of ultrasonic motors are expected.
For example, Japanese Patent Application Laid-Open No. 2005-143176 discloses a rotational drive apparatus shown in FIG. 7. The rotational drive apparatus is composed of a vibration member 20, a frame 23 for the vibration member, a vibration member support means 24, a leaner stage 25, an arm 22, a zirconia ball 21 having a substantially spherical surface, an annular member 29, and other components and can be driven about multiple axes.
In this prior art apparatus, the linear stage 25, a screw 27 serving as a mechanism for applying pressure, a spring 28, the zirconia ball 21, and the annular member 29 are attached to the arm 22. In consequence, these components have respective degrees of freedom of assembly.
Therefore, this apparatus suffers from the problem that it requires great efforts to align the center axis L of the apparatus and the axes of the aforementioned components as assembled.